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Microbiology > Day 4: Microscopy and Staining > Flashcards

Day 4: Microscopy and Staining Flashcards

1
Q

What are the 3 properties of light

A

1) wavelength
2) amplitude
3) frequency

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2
Q

Define wavelength

A

most important aspect

1 peak to the peak ( distance)

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3
Q

Define amplitude

A

height of peak

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4
Q

Define reflection

A

wave bounces off

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5
Q

Define absorbance

A

wave is captured

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6
Q

Define transmission/transmittsnce

A

wave travels through

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7
Q

Define resolution

A

ability of the lenses to distinguish fine detail and structure
( ability of the lenses to distinguish two parts that are a specified distance apart)

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8
Q

Define refraction

A

light wave changes direction as they enter a new medium

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9
Q

Define refractive index

A

a measure of the light bending ability of a medium

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10
Q

Define lenses

A

light passes through concex lens

refracted to a focal point

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11
Q

What did Antoine Van Leewenhoek contribute to microschopes

A

simple microscopre

animalcules

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12
Q

What did Robert Hooke contribute to early microscopes

A

compound microscope

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13
Q

Define light microscope

A

any kind of microscope that uses visible light to observe specimens

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14
Q

What are the different types of light microscopy

A 
Brightfield
Darkfield
phase-contrast
differential interference contrast ( DIC) 
fluorescence microscopy
confocal
two-photon
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15
Q

Describe the bright field microscopy

A

compound microscope
dark image on bright background
monocular or binocular

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16
Q

Define magnification

A

ability to enlarge images

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17
Q

Define total magnification

A

objective lens( 10x) x ocular lens( 4x, 10x,40x,100x)

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18
Q

Define resolution

A

ability to tell that 2 separate points or objects are separate

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19
Q

What are 2 factors affecting resolution

A

wavelength

numerical aperture

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20
Q

How do we prevent refraction in compound microscope

A

use of immersion oil ( light unrefracted)

w/o immersion oil ( most light is refracted and lost)

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21
Q

Define contrast

A

visible difference between the parts of a specimen

use different dyes and stains

22
Q

What are the 2 types of preparation

A

1) wet mount

2) fixed preparations

23
Q

Describe the wet mount technique

A

specimen is placed on the slide in a drop of liquid

24
Q

Define staining

A

coloring microorganisms with a dye to increase contrast

25
Q

Define smear

A

thin film of a material containing microorganisms spread over a slide

26
Q

Define fixed preparations

A

attaching cells to the slide

kills cells

27
Q

What are the 2 types of fixed preparations

A

1) heat fixing

2) chemical fixing

28
Q

Define heat fixing

A

smear is prepared and briefly heated

29
Q

Define chemical fixation

what chemicals? What is it used for? How does it work?

A

acetic acid, ethanol,methanol,formaldehyde
mainly used for tissues
denatures the proteins

30
Q

What ions are consist in staining

A

stains are salts composed of positive and negative ions

31
Q

What is chromophore

A

positive or negative ions that stain
positively charged chromophore is a basic dye
negatively charged chromophore acidic dye

32
Q

What are examples of positive basic dyes(5)

What do they dye? cell or background? why?

A

cation in this basic dye is attracted to the negatively charged bacterial cell
basic fuchsin, crystal violet, malachite green, methylene blue, and safranin

33
Q

What is counterion

A

uncolored staining

34
Q

What are examples of acidic dye ( 3)

What does the dye stain? Why does it stain this way?

A

negatively charged chromophore
ex. acid fuchsin, eosin,rose bengal
stain is repelled by cell wall so don’t stain cell wall, instead dyes the background
dye is negative and bacteria is negative so repel

35
Q

What are the 2 types of stain

A

positive and negative

36
Q

Define positive stain

A

staining the cells or organisms being observed

most commonly used

37
Q

Define negative stain

What are we observing with this?

A

staining the background instead of the cell

valuable for observing overall cell shapes,size, and capsule

38
Q

What are the 2 types of staining technique

A

simple staining

differential staining

39
Q

What is simple staining

what are 4 examples

A

`primary purpose is to highlight the entire microorganism so that cellular shapes and basic structures are visible
ex.methylene blue, carbolfuchsin, crystal violet,safranin

40
Q

define differential staining

A

distinguishes organism based on their interactions with multiple stains

most common stains caused for bacteria are gram stain and acid fast stain

41
Q

What are the 3 differential staining techniques

A

gram staining
acid-fast staining
endospore staining

42
Q

Describe gram staining

A
  • classifies bacteria into gram-positive or gram-negative
    -based on the difference in cell wall composition
    ( gram positive: thick peptidoglycan cell wall)
    ( gram-negative: thin peptidoglycan cell wall)
43
Q

Describe acid fast staining

A

differentiate gram positive bacteria with waxy lipid ( mycolic acid) bound yo peptidoglycan

44
Q

What stain is used in acid fast staining

A

carbolfuchsin

45
Q

What are the 2 techniques of acid fast staining

A

Ziehl-Neelsen and Kinyoun Technique

46
Q

What bacteria can we use acid fast staining for

A

genus: bacteria mycobacterium
genus: nocardia

47
Q

Describe the endospore staining

A

primary stain: malachite green
counterstain: safranin
if stained with malachite green will have endospores

48
Q

What is the method called in endospore staining

A

Schaeffer-Fulton method

49
Q

What bacteria can we use endospore staining for

A

bacillus and Clostridium

50
Q

Describe the capsule staining

A

capsule protective outer gelatinous covering
negative staining ( dye as white outline of bacteria)
stains used are India ink or nigrosin

51
Q

Describe flagella staining

A

flagella-tail like structure used for locomotion

uses a mordant + pararosaniline or carbolfuchsin

Microbiology (16 decks)

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